getportname
extern char *getportname(int, in_port_t);
pn = getportname(proto, src);
pn = getportname(proto, dst);
pn = getportname(IPPROTO_SCTP, (ushort_t)sport);
pn = getportname(IPPROTO_SCTP, (ushort_t)dport);
pname = getportname(IPPROTO_TCP, ntohs(tcp->th_dport));
pname = getportname(IPPROTO_UDP, ntohs(udp->uh_dport));